An image reading apparatus, including an image sensor configured to receive light and output an image signal in accordance with image data carried in the light, an A/D converter configure to convert the image signal into a digital signal with reference to a reference voltage, and a reference white plate configured to be read so as to generate density data. Also included is a correction device configured to correct the digital signal in accordance with shading data, a reference member configured to define a readable density limit, and a detection device configured to detect a ratio of density of the reference white plate to that of the reference member as density adjustment data. The density is obtained by reading the respective reference member and reference white plate in substantially a same exposure condition. Further included is a control device configured to control the correction device to adjust the digital signal in accordance with the density adjustment data.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An image reading apparatus, comprising: an image sensor configured to receive light and output an image signal in accordance with image data carried in the light; an A/D converter configure to convert the image signal into a digital signal with reference to a reference voltage; a reference white plate configured to be read so as to generate density data; a correction device configured to correct the digital signal in accordance with shading data; a reference member configured to be read so as to define a readable density limit, said readable density limit correcting density data obtained by reading the reference white plate; a detection device configured to detect a ratio of density of the reference white plate to density of the reference member as density adjustment data, said density being obtained by reading the respective reference member and reference white plate in substantially a same exposure condition; and a control device configured to control the correction device to adjust a density of the digital signal in accordance with the density adjustment data.
2. The image reading apparatus according to claim 1 , further comprising a nonvolatile memory configured to store the density adjustment data.
3. The image reading apparatus according to claim 1 , wherein said correction device adjusts the shading data in accordance with the density adjustment data and performs shading correction and shading correction.
4. The image reading apparatus according to claim 3 , further comprising a multiplication and division circuit configured to perform the adjustment of shading data by the correction device.
5. The image reading apparatus according to claim 3 , further comprising an addition and subtraction circuit.
6. The image reading apparatus according to claim 5 , further comprising an addition and subtraction circuit.
7. The image reading apparatus according to claim 1 , further comprising: a user interface configured to operate the image reading apparatus; and a detection mode starting device configured to start a detection mode so as to detect the density adjustment data through an operation of the user interface.
8. The image reading apparatus according to claim 1 , further comprising a determining device configured to determine an abnormality of the reference white plate, said abnormality being detected when the density adjustment data is larger than a prescribed value.
9. The image reading apparatus according to claim 8 , further comprising a display configured to display a result of the determination of abnormality on a user interface.
10. The image reading apparatus according to claim 1 , wherein density adjustment data is manually set through a user interface.
11. The image reading apparatus according to claim 1 , wherein said correction device performs shading correction and adjusts image data obtained from an original before or after shading correction in accordance with the density adjustment data.
12. The image reading apparatus according to claim 11 , further comprising a multiplication and division circuit configured to perform the adjustment of shading data by the correction device.
13. An image forming system, comprising: an image reading apparatus including an image sensor configured to receive light and output an image signal in accordance with image data carried in the light, an A/D converter configure to convert the image signal into a digital signal with reference to a reference voltage, a reference white plate configured to be read so as to generate density data, a correction device configured to correct the digital signal in accordance with shading data, a reference member configured to be read so as to define a readable density limit, said readable density limit correcting density data obtained by reading the reference white plate, a detection device configured to detect a ratio of density of the reference white plate to density of the reference member as density adjustment data, said density being obtained by reading the respective reference member and reference white plate in substantially a same exposure condition, and a control device configured to control the correction device to adjust a density of the digital signal in accordance with the density adjustment data; and an image formation apparatus configured to form an image in accordance with an output of the image reading apparatus.
14. The image forming system according to claim 13 , wherein the image reading apparatus further comprises a nonvolatile memory configured to store the density adjustment data.
15. The image forming system according to claim 13 , wherein said correction device adjusts the shading data in accordance with the density adjustment data and performs shading correction and shading correction.
16. The image forming system according to claim 15 , wherein the image reading apparatus further comprises a multiplication and division circuit configured to perform the adjustment of shading data by the correction device.
17. The image forming system according to claim 15 , wherein the image reading apparatus further comprises an addition and subtraction circuit.
18. The image forming system according to claim 17 , wherein the image reading apparatus further comprises an addition and subtraction circuit.
19. The image forming system according to claim 13 , wherein the image reading apparatus further comprises, a user interface configured to operate the image reading apparatus; and a detection mode starting device configured to start a detection mode so as to detect the density adjustment data through an operation of the user interface.
20. The image forming system according to claim 13 , wherein the image reading apparatus further comprises a determining device configured to determine an abnormality of the reference white plate, said abnormality being detected when the density adjustment data is larger than a prescribed value.
21. The image forming system according to claim 20 , wherein the image reading apparatus further comprises a display configured to display a result of the determination of abnormality on a user interface.
22. The image forming system according to claim 13 , wherein density adjustment data is manually set through a user interface.
23. The image forming system according to claim 13 , wherein said correction device performs shading correction and adjusts image data obtained from an original before or after shading correction in accordance with the density adjustment data.
24. The image forming system according to claim 23 , wherein the image reading apparatus further comprises a multiplication and division circuit configured to perform the adjustment of shading data by the correction device.
25. An image reading apparatus, comprising: image sensor means for receiving light and output an image signal in accordance with image data carried in the light; A/D converter means for converting the image signal into a digital signal with reference to a reference voltage; reference white plate means for reading so as to generate density data; correction means for correcting the digital signal in accordance with shading data; reference means for being read so as to define a readable density limit, said readable density limit correcting density data obtained by reading the reference white plate means; detection means for detecting a ratio of density of the reference white plate means to density of the reference means as density adjustment data, said density being obtained by reading the respective reference means and reference white plate means in substantially a same exposure condition; and control means for controlling the correction device to adjust a density of the digital signal in accordance with the density adjustment data.
26. The image reading apparatus according to claim 25 , further comprising memory means for storing the density adjustment data.
27. The image reading apparatus according to claim 25 , wherein said correction means adjusts the shading data in accordance with the density adjustment data and performs shading correction and shading correction.
28. The image reading apparatus according to claim 27 , further comprising multiplication and division means for performing the adjustment of shading data by the correction means.
29. The image reading apparatus according to claim 27 , further comprising addition and subtraction means.
30. The image reading apparatus according to claim 29 , further comprising addition and subtraction circuit means.
31. The image reading apparatus according to claim 25 , further comprising: user interface means for operating the image reading apparatus; and detection mode starting means for starting a detection mode to detect the density adjustment data through an operation of the user interface means.
32. The image reading apparatus according to claim 25 , further comprising determining means for determining an abnormality of the reference white plate means, said abnormality being detected when the density adjustment data is larger than a prescribed value.
33. The image reading apparatus according to claim 32 , further comprising display means for displaying a result of the determination of abnormality on a user interface means.
34. The image reading apparatus according to claim 25 , wherein density adjustment data is manually set through user interface means for operating the image reading apparatus.
35. The image reading apparatus according to claim 25 , wherein said correction means performs shading correction and adjusts image data obtained from an original before or after shading correction in accordance with the density adjustment data.
36. The image reading apparatus according to claim 35 , further comprising multiplication and division means for performing the adjustment of shading data by the correction means.
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July 23, 2002
October 7, 2008
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